Eruvin 99: Polite Company

One who urinates or spits from the private domain to the public domain seems to need to bring a sacrifice. But how does this act of transfer include both uprooting from the one place and coming to rest in a new place? Perhaps the person's thinking compensates for the lack of a defined space. Specifically, leaving and landing in a space of 4 tefachim, or that one's aim indicates that the 4 tefachim are not critical. [What's What: Truly, again?] Also - Resh Lakish on public spitting. Also - Thr wine press's that's near the junction of public and private domains. How formal is your drinking in this locale? What makes it formal, as compared to incidental? And how does this lead into the next mishnayot? Regarding a gutter, a cistern, an embankment for garbage.